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From Todd Lipcon <t...@cloudera.com>
Subject Re: Feature request for Kudu 1.3.0
Date Fri, 10 Feb 2017 21:12:31 GMT
On Fri, Feb 10, 2017 at 10:32 AM, Weber, Richard <riweber@akamai.com> wrote:

> I definitely would push for prioritization on this.
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> Our main use case is less about multiple racks and failure, and more about
> functionality during the install process.  Our clusters are installed in
> logical regions, and we install 1/3 of a region at a time.  That means 1/3
> of the cluster can be down for the SW install, reboot, or something else.
> Allowing rack locality to be logically defined will allow the data to still
> be available during normal maintenance operations.
>
>
That's an interesting use case. How long is the 1/3rd of the cluster
typically down for? I'd be afraid that, if it's down for more than a couple
minutes, there's a decent chance of losing one server in the other 2/3
region, which would leave a tablet at 1/3 replication and unavailable for
writes or consistent reads. Is that acceptable for your target use cases?

There are certain things we could consider doing to allow a replica to fall
to 1/3 while still remaining online, but don't think we've considered doing
them any time particularly soon. Would be good to get data on how important
that is.

-Todd




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> -- Rick Weber
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> *From: *Todd Lipcon <todd@cloudera.com>
> *Reply-To: *"user@kudu.apache.org" <user@kudu.apache.org>
> *Date: *Friday, February 10, 2017 at 12:45 PM
> *To: *"user@kudu.apache.org" <user@kudu.apache.org>
> *Subject: *Re: Feature request for Kudu 1.3.0
>
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> Hi Jeff,
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> Thanks for the input on prioritization.
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> I'm curious: do you have more than two racks in your cluster? With Kudu's
> replication strategy, we need at least three racks to be able to survive a
> full rack outage. (with just two racks it's impossible to distinguish a
> loss of a rack with a partition between the two racks).
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> -Todd
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> On Fri, Feb 10, 2017 at 7:27 AM, Jeff Dasch <jeff_dasch@yahoo.com> wrote:
>
> Any chance we can get a fix for KUDU-1535 "Add rack awareness" added to
> the 1.3.0 release?
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>
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> While I appreciate the need for Kerberos and TLS for some production
> systems, for my use-case data availability really takes priority.
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> I looked at your scoping document, and for what it's worth, I'm fine with
> a shell script that is similar to what Hadoop uses.
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> thanks,
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> -jeff
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> --
>
> Todd Lipcon
> Software Engineer, Cloudera
>



-- 
Todd Lipcon
Software Engineer, Cloudera

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